docs: def _get_filename(self):
          """Get the rsr filname from platform and instrument names, and download if not
             available.
  
          """
          self.filename = expanduser(
              os.path.join(self.rsr_dir, 'rsr_{0}_{1}.h5'.format(self.instrument,
                                                                 self.platform_name)))
  
          LOG.debug('Filename: %s', str(self.filename))
          if not os.path.exists(self.filename) or not os.path.isfile(self.filename):
              LOG.warning("No rsr file %s on disk", self.filename)
  
              if self._rsr_data_version_uptodate:
                  LOG.info("RSR data up to date, so seems there is no support for this platform and sensor")
              else:
                  # Try download from the internet!
                  if self.do_download:
                      LOG.info("Will download from internet...")
                      download_rsr()
                      if self._get_rsr_data_version() == RSR_DATA_VERSION:
                          self._rsr_data_version_uptodate = True
  
          if not self._rsr_data_version_uptodate:
              LOG.warning("rsr data may not be up to date: %s", self.filename)
              if self.do_download:
                  LOG.info("Will download from internet...")
                  download_rsr()